Nowadays, the photovoltaic power is widely used on residential and commercial roof. A typical photovoltaic power generation system includes photovoltaic arrays, several junction boxes and an inverter, or the like. The photovoltaic array is configured to convert the harvested solar energy to DC (direct current) power. The inverter is used to convert the DC power to the desired AC (alternating current) power, to be on-grid or directly supplied to local load. A DC switch inside the junction box is used to shut down the input of a DC voltage from the photovoltaic array to the inverter.
The photovoltaic arrays connected in series and parallel bring high voltage and energy. When an emergency event (an earthquake, fire, or the like) occurs, the National Electric Code (2014, 2017) requests that the photovoltaic array with high voltage and high energy needs to be disconnected, to prevent the further hazards.
However, the DC switch in the junction box may only guarantee that no DC voltage will be connected to the inverter. Photovoltaic panels in the photovoltaic array still have high open-circuit output voltage. Still there is the risk of electric shock.
Currently, rapid shutdown devices are usually connected to the photovoltaic power generation system in series. A photovoltaic power generation system in the prior art is shown in FIG. 1. The photovoltaic power generation system 10 includes a plurality of photovoltaic arrays 11, a shutdown device 12, a junction box 13 and an inverter 14. The shutdown device 12 is connected in series between the output terminal of the photovoltaic arrays 11 and the DC input terminal of the inverter 14. With this connection type, the disconnecting element of the shutdown device 12 is in a closing state for a long time. During normal operation, the current flowing through the shutdown device 12 is quite large, so the disconnecting element may have a large heat generation due to the voltage drop on it, and the lifespan of the disconnecting element is vulnerable. In addition, the series-type shutdown device has high requirement on voltage endurance capability and current flow capability of disconnecting elements. Therefore, the volume of the shutdown device is relatively large and the cost is relatively high.
Therefore, a novel arrangement manner is required to rapidly shutdown the photovoltaic array.
The above information disclosed in the BACKGROUND is merely for better understanding of the context of the present disclosure, and may include contents that do not constitute the known prior art of those skilled in the art.